Liquid-break circuit interrupter



Dec. 9, 1952 R. E. FRIEDRICH EI'AL 2,621,273

LIQUID-BREAK CIRCUIT INTERRUPTER Filed April 28, 1950 2 SI-lEETS--SHEET l Fig.2.

WITNESSES: INVENTORS Robert E. Friedrich 8; W Curl G. Lemjes. w e M a #W ATTORNE Dec. 9, 1952 R. E. FRIEDRICH ETAL 2,621,273

LIQUID-BREAK CIRCUIT INTERRUPTER Filed April 28. 1950 2 SHEETSSHEET 2 Fig.4.

INVENTORS Robert E Friedrich 8 Carl G. Lenijes.

Patented Dec. 9, 1952 LIQUID-BREAK CIRCUIT INTERRUPTER Robert E. Friedrich and Carl G. Lentjes, Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 28, 1950, Serial No. 158,892

Claims.

This invention relates to circuit interrupters, in general, and more particularly to arc-extinguishing structures therefor of the liquidbreak type.

A general object of our invention is to provide an improved piston construction for a circuit interrupter of the liquid-break type.

Another object is to provide an improved piston construction for a circuit interrupter of the type establishing a pressure-generating break and a serially related interrupting break.

A more specific object is to provide an improved piston construction for a liquid-break type of circuitinterrupter in which the piston is at least partly of the circulating type, and providing the location of the piston arrangement in such relation to the pressure-generating gap that a minimum length of liquid flow travel is involved.

Still another object is to provide a circuit interrupter having an improved piston construction in which the piston is not only of the circulating type with the arcing pressure substantially balanced thereon, but the piston has means for causing in addition to the circulating flow, a positive diminution of liquid within the piston chamber to thereby effect a positive sending of fluid through passages into the pressure break and along toward the interrupting break to pass out of the interrupter.

Further objects will be readily apparent upon reading the following specification taken in conjunction with the drawings, in which:

Figure 1 is a side elevational view, partially in vertical section, of a circuit interrupter embodying our invention and shown in the closed circuit position;

Fig. 2 is an enlarged vertical sectional view through the left-hand arc-extinguishing unit of the interrupter shown in Fig. l, with the contact structure being illustrated in the closed circuit position; v

Fig. 3 is a fragmentary vertical sectional view taken along the line III-III of Fig. 2;

Fig. 4 is a view similar to that of Fig. 2, but showing the disposition and arrangement of the parts at an intermediate point in the opening operation; and

Fig. 5 is a fragmentary vertical sectional view taken along the line V-V of Fig. 4.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numeral l designates a tank filled to the level 2 with a stance circuit breaker oil. Depending from the cover 4 of the tank I are a pair of terminal bushings 5, 6 to the lower ends of which are secured arc-extinguishing units, generally designated by the reference numeral 1 and electrically interconnected, in the closed circuit position shown, by a conducting cross-bar 8. The cross-bar 8 is actuated reciprocally in a vertical direction by an insulating operating rod 9.

Referring to Figs. 2 and 4, which more clearly show the internal construction of the arc-extinguishing unit I, it will be noted that clamped to the lower end of the terminal stud I0 is a clamp H which is bolted by bolts I2 to a top dome casting l3. Movable within the top dome casting l3 interiorly thereof is a rotatable pressure-generating contact [4. In the closed circuit position, shown in Fig. 2, the pressuregenerating contact I 4 engages an intermediate contact [5, the latter in turn engaging a lower interrupting rod-shaped contact [5 secured to the extremity of the cross-bar 8.

During the opening operation, the rotatable pressure-generating contact [4 separates upwardly away from the intermediate contact to establish therebetween a pressure-generating are I! more clearly shown in Fig. 4. Also, an interrupting arc i8 is established between the intermediate contact l5 and the lower movable interrupting contact it. These two breaks are established practically simultaneously.

An insulating operating rod I9 is provided movable longitudinally of the unit 1, laterally thereof. The lower end of the operating rod l9 abuts against the cross-bar 8 and is forced by the latter upwardly during the closing operation against the biasing action exerted by an accelerating compression spring disposed at the upper end of the operating rod [9. The compression spring 20 seats at its upper end against the bight portion 2| of a bracket 22, the latter forming an integral part of an apertured cap 23. The cap 23 is secured by any suitable means, such as by welding, to the top dome casting I 3.

The pressure-generating contact 14 is rotatable, being pivotally mounted on a fixed removable pivot pin 24, the outer ends of which are journaled in the side walls of the top dome casting [3. The right-hand end of the rotatable pressure-generating contact I4 is bifurcated, and, referring to Fig. 3, the legs 25 of the right-hand forked end of the pressure-generating contact I4 have open slots 26 formed therein. Within the open slots 26 disposed at the extreme right-hand ends of the legs 25 of the pressure-generating contact 14 are bosses 21, the latter forming an integral part of a sleeve 28. The sleeve 28 slidably surrounds the operating rod l9 and has its upper end threadedly secured at 29 to an apertured cup-shaped member 38. Disposed within the cup-shaped member 36 is a compression spring 3| which serves to provide the requisite contact pressure between the several contacts H5, H5, and It. In other words, a shoulder 32 is formed upon the operating rod 19 which supports a washer 33 near the end of the closing stroke engaging the compression spring 3| as shown in Fig. 2. During the closing operation, "after the contacts H3, and I6 have made contacting engagement, the operating rod is may continue slightly upwardly in its closing motion to :thereby slightly compress the compression spring 3!. Thus, the compression spring 3i forms the contact pressure for the several contacts.

A piston chamber 34 is formed integrally with the top dome casting l3. fA piston 35 of the circulating type is'disposed within thepiston chamber 34, and hasits lower or working face 36 operative to force liguid downwardly in the direction'of the arrows 37 (Figs. 2 and 3) through a passage means 3t interconnecting the piston chamber 34 with the pressure-generating are 17. Fig. 3*more clearly shows thatthe lowerend'of the piston chamber 34is expanded, as at 39, forming two conduits toregisterwith openings Min the plate structure. The openings dflcommunicate with a passage ll which, at its lefthand end, communicates radially, as at 62, with anorifice 43, through which'the pressure-generating are H: is drawnby cooperation-ofthe pressurergenerating and intermediate contacts is and I5. h

The pressure-generating chamber, generally designated by the reference numeral A L-and essentially defined bythe topdome casting l3, communicates by a plurality of in, this instance three, passages i5 with two vertical flow passages, generally designated by the reference numeraldfi, the latter in turn communicating with' a plurality of pairs otinletpassages 41. The inlet passages *ljlead to aplurality of orifices 48, through which the, interruptingarc IB'is drawn by co operation of the intermediate and interrupting contacts i5, [6. On :the opposite sides of the orifices 48 from the inlet passages 4'1 are disposed vent passages 49, which lead-directlynut of the unit 7 in a direction perpendicularto the plane of the drawings. Th-e'interrupting cham ber 59 has a configuration more clearly set forth in us. Patents 2,406,469 and 2,467,760,' issued to,

Leon ,3. Ludwig, BenjaminP. Baker and 'Winthrop M. Leeds, and assigned to the assignee of the instant application. Consequently, reference may-be hadfto these two patents'for details of the interrupting structure 5 0, and since the present invention islnot concerned with those details only a cursory description of the plate structure ishere presented. V A

The upper end lof the insulating'operating rod l9;has forced thereupon a metallic endportion 5l .;hav ing a, should er 52 upon which seats a asher 5 .ll% 1l 7i 3 is de l o the endportion5i. N Seated upon the washer'53 is a compression spring 54, the upper end of which seats against an inturn ed flange 55 forming the.

upper end'ofiatubulafmember 56. The'side walls of the tubular member 56 havevertical'slots 5! (Fig.3) formed therein permitting a communication between 'the'region 58 and the passage means 38. The lower end of the cylindrical'mem-.

ber 55"has'an cutturnednange' 59"w'h'ich rests 4 about the opening 60 formed at the lower end of the piston chamber 34.

The compression spring 54 has, as one of its purposes, the maintenance of the cylindrical member 56 within the opening 60 in a stationary position. Another function of the compression spring 55 is .to initially help the spring 23 in moving the rod [9 downwardly. Also the spring 54 moves the pressure contact [4 to the open circuit position, as shown in Fig. 4.

A cylindrical extension 62, upon which the adjusta-blenuts 6| are threaded, has a lower protruding end 64 inserted by a press fit within the upper cylindricalportion 65 of the end 5| of the operating rod t9. A locking pin 56 is inserted,

and a sets'crewii't locks the locking pin 66 in a set position. The cylindrical extension 62 may alsoserve'as a'housing for the compression spring It will be observed that the circulating piston 35 has an upwardly extending cylindrical portion, or member of enlarged cross-sectional area 61 movable therewith, the latter having an inturned flange 68 integrally formed therewith. During the opening operation, the nuts 5| engage the flange 68 at the upper end of the piston-35 with a delayed action. Consequently, there-is a lost-,

motion connection 69'between the-operating-rod l9 and the circulatingpiston 35. -It will-also be noticed that the cylindrical extension '62 has .a shoulder Ill formed thereupon, which picks up the flange 58 of the piston 35 during the closing operation. A relatively light compression spring H, seated between the piston *35 and the cap 23, serves to bias the piston 35 downwardly so that" the flange 68 is constantly seated against the shoulder ll) .i-nthe closed circuit position'of the interrupter. Asa result of this construction, there is always the same amount of desired time lag associated with the lost-motion connection 69 beforethe nuts 6! pickup-the flange 68, and hence the-piston 35, and-carry the latter down.- war-dly'therewi-th,

Associated with the pressure-generating chamher- 44 isa-n-overpressure valve 12 and a normally open-gas relief valve 13. It will be observed that the pin 24, upon which-the pressure-generating contact l4 -;is rotatably mounted, may .be removed out of the casting- 13 so as topermit the pressure-generating contactto 'be removed out of the pressure-generating chamber '44 through the 5 side "opening Miollowing removal of' the side plate 15 and after detachment of'the-shunt' lead 16; from its boltedconnection at 11 to the casting I 3. y

The operation of our improved interrupter-will now be described. In the closed circuit position of the interrupter, shown in Figs. 1, 2 and 3, the electrical circuit extending therethrough includes terminal stud-l0,- conducting clamp- I l, conducting casting l3, flexible shunt-16,pressure-generating contact [4, intermediate contact I5,- lower movable interrupting contact l6, and through the conducting-cross=par-8 to the right-hand arc-extinguishing unit 1. The electrical circuit extends in a similar manner through; the righthand arc-extinguishing unit 1- to the right-hand terminal stud of the interrupter.

During the opening operation, either 'in response to manual operation-orin response '-to overload conditions existing in the circuit controlled by the interrupter, suitable mechanism, not shown,-is operative to-cause downward opening motion of the-insulating lift rod 9.

Thedownward opening motion ofthe lift rod 9 causes corresponding downward opening movement of the cross-bar 8 and both interrupting contacts I6 at its opposite extremities. Considering only one unit 1, it will be apparent that downward motion of the cross-bar 8 and movable interrupting contact I6 permits the accelerating compression spring to force the operating rod I9 downwardly so that the lower end thereof maintains contact with the cross-bar 8. Spring 54 serves initially to accelerate rod I9, and may continue to do so during the remainder of the opening stroke of the pressure-generating contact I4. The contacts I4, I5 and I6 remain in engagement due to the compression of the compression spring 3| until the washer 53 strikes the top of the cup-shaped member 30. By this time, the compression spring 3| is only slightly stressed, and the sleeve 28 then moves downwardly solely under the biasing action exerted by spring 54.

Since the bosses 21 are integrally formed with the sleeve 28, the bosses 21 move downwardly carrying the legs 25 therewith, and thus rotating the pressure-generating contact |4 about its pivot 24 drawing a pressure are II. Substantially simultaneously with the separation of the contacts I4, I5, the contact I6 separates from the contact I5 to establish an interrupting are I 8, more clearly shown in Fig. 4. As a result, there is a practically simultaneous formation of a This pressure forces oil downwardly through the passages 45 into the vertical flow passages 46, through the inlet passages 41, into engagement with the interrupting arc I8 and through the orifices 48 to exhaust out of the unit I through the laterally disposed vent passages 49.

Because of the provision of a lost motion connection 99 between the operating rod I9 and the circulating piston 35, there is delayed pumping of oil through the passages 38, 49 and 42 into the pressure-generating are II. This delayed pumping brought about by the provision of the lost-motion connection 69 has the advantage that the time delay may be such as to fall within the teachings of United States Patent 2,592,635, issued April 15, 1952. As set forth in this patent, such a time delay greatly assists in bringing about charging current interruptions.

When the operating rod I 9 has traveled downwardly far enough so that the nuts 6| do engage the flange 68, the circulating piston will, at this time, be under the biasing action exerted by the accelerating compression spring 20. This downward biasing action exerted by the compression spring 20 will be slightly assisted by the relatively light compression spring II, which normally maintains the flange 68 against the shoulder III in the closed circuit position to bring about the desired time delay.

Even though rotation of pressure contact |4 may be halted by sleeve 28 striking the stop 83, the rod I9 continues to move downwardly under biasing action exerted by compression spring 20.

It will be observed that the circulating piston 35 has its lower or working face 36 exposed to the arcing pressure through the passage means 39, passages 40, passages 4| to the pressure-generating are II. It will also be observed that the top or non-working face I9 of the circulating piston .35, of annular area C (Fig. 4), is also 6 exposed to the arcing pressure by virtue of an opening 89 provided in the piston chamber 34. Since, therefore, arcing pressure acts on both sides 36, I9 of the circulating piston 35, the pressure of the springs 20 and II need be such only as to overcome liquid friction through the passages. Since the entire piston assembly is disposed near to the pressure-generating arc II, the length of the passages is short, and liquid friction through these passages is held to a minimum.

In addition to the circulating oil flow of annular area 0" caused by operation of the circulating piston 35, it will be observed that a cross-- sectional area A, or cross-sectional area of the operating rod I9 moves out of the piston chamber 34. Also, it will be observed that an enlarged cross-sectional area B or cross-sectional area of the cylindrical portion SI of piston 35 moves into the piston chamber 34, so that, in addition to the circulating flow, there is a positive diminution or lessening of liquid volume within the piston chamber 34 to thereby bring about a positive displacement of liquid out of the piston chamber 34 through the passages 38, 49 and 4| into the pressure-generating arc II, and onwardly through the passages 45, 45, 4! and 49 out of the arc-extinguishing unit I.

Thus, we have provided two types of flow resultin from the operation of our improved piston assembly. The first type of flow of annular area C is a circulating oil flow through the pressure-generating are I! and back to the piston 35. However, the second type of flow is a positive displacement of liquid out of the piston chamber 34, and hence this type of flow results in a complete displacement of liquid out of the arc-extinguishing unit I. It is equivalent to a piston of area B-A forced into the piston chamber 34 or forced into the unit I to result in the displacement of oil out of the unit I. In other words, this second type of flow, the displacement type, sends a liquid flow sequentially through the pressure-generating are I I and onwardly into the interrupting arc I8, and thence out of the interrupting unit I through the vent passages 49.

During the opening operation, the gas relief valve I3 closes, as shown in Fig. 4, and under excessive pressure, the valve I2 will open. In the closed position of the interrupter, the gas relief valve I3 opens, upon a subsidence of pressure within the pressure-generating chamber 44 to permit an exit of gas out of the pressure-generating chamber 44 through the gas relief valve I3.

During the closing operation, the lift rod 9 and cross-bar 8 move upwardly, picking up the operating rod I9 to move the latter upwardly. The upward motion of the operating rod [9 continues until the several contacts I4, I5 and I6 make engagement, at which time further continued upward movement of the operating rod l9 effects a compression of the contact compression spring 3| to thereby eifect the requisite contact pressure between the several contacts. During the upward motion, the shoulder E0 on the operating rod I9 has picked up the piston 35 and charged it, the compression spring II maintaining the flange 68 against the shoulder ID. Furthermore, the shoulder 52 on rod I9 picks up the slidable washer 53 and compresses the spring 54, thereby ensuring that the cylinder 55 is maintained within the opening 69 of piston chamber 7 34 with the flange .59 thereof against the lower face 81 of the piston chamber 34.

From the foregoing description of our improved interrupter, it will be apparent that we have provided an improved piston construction for a liquid break type of circuit interrupter, particularly one establishing a pressure-generating arc and a serially related interrupting arc. it will be observed that we have not only provided a circulating flow, thereby reducing the spring pressures involved since arcing pressure acts on both sides of the circulating piston 35, but also, in. addition to the circulating flow, we -have provided a positive displacement or diminution of liquid volume within the piston chamber '34 to actually displace liquid out of the unit I. This latter positive forced liquid how is sent sequentially through the pressure-generating arc i7 and onwardly through the interrupting are it and out of the unit 1.

From the foregoing, it will, therefore, be apparent that we have provided two types of flow. a circulating flow especially efiecting interruption of the pressure-generating are H, and a net displacement or lessening of liquid volume within the piston chamber 35 to efiect interruption of the interrupting arc 18, since such a type of flow directly eiiects both arcs in its sequential travel.

Further, it will be observed that the piston assembly is disposed immediately adjacent to the pressure-generating are H so that liquid frictional losses are held to a minimum through the several passages. In addition, it will be observed that the piston assembly is operated. by operation of the operating rod l9 and thereby entails no additional complicating driving mechanisms to effect operation of the piston structure.

The provision of such improved piston means results .in improved performance during the interruption of line charging or capacitor currents since the liquid flow enters the arc region at the proper time. It also results in a flow of oil through the interrupting are, as well as a circulating flow of oil through the pressure-generatmg arc.

The delayed pumping of the piston 3-5 results in the pressure-generating break H being established before operation of the piston. Consequently, even though the piston 35 may during a portion of its later travel be backed up by high arcing pressures, still the contacts [4, [5 will not be forced closed. In addition, it may be noted that the compression spring 23, which actuates the piston 35, is eiiective in accelerating the operating rod l9 prior to the start of pumping, thus getting a greater use-factor for the spring.

Although we have shown and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

' We claim as our invention:

1. A circuit interrupter including a pressuregenerating contact, an intermediate contact and an interrupting contact, the pressure-generating and intermediate contacts cooperating to establish a pressure-generating arc, the intermediate and interrupting contacts cooperating to establish an interrupting are, an operating rod for actuating the pressure-generating contact, a piston chamber, a piston movable within thepiston chamber and having its two sides exposed to the arcing pressure, passage means communicat mg the piston chamber on the working side thereof only with the pressure-generating are, means biasing the operating rod in a direction to move liquid toward the pressure-generating arc, means interconnecting the operating rod with the piston, a member of relatively enlarged cross sectional area movable with the operating rod and a member of relatively small cross-sectional area movable thereby, and. the operating rod be ing movable through the piston chamber so that theenlargedmember enters the piston chamber as the smaller member leaves the piston chamber so that a positive diminution of liquid takes place within the piston chamber. I

*2.1% circuit interrupter including a pressuregenerating contact, an intermediate contact and an interrupting contact, the pressure-generating and intermediate contacts cooperating to estab-' lish a pressure generatin'g are, the intermediate and interrupting contacts cooperating to establish an interrupting are, an operating rod for actuating the pressure-generating contact, a piston chamben-a piston movable within the piston chamber and having its two sides exposed to the arcing pressure, passage means communicating the piston chamber on the working side thereof only with the pressure-generating are, means biasing the operating rod in a direction to move liquid toward the pressure-generating arc, means interconnecting the operating rod with the piston, a member of relatively enlarged cross-sectional area movable with the operating rod and a member of relatively small cross-sectional area movable thereby, the operating rod beingmova- 'le through the piston chamber so that the enlarged'm'ember enters the piston chamber as the smaller member leaves the piston chamber so that a positive diminution of liquid takes place within the piston chamber, and the interconnecting means betwen the operating rod and the piston utilizing a lost-motion connection.

3. A circuit interrupter including a pressureg'enerating contact, an intermediate contact and an interrupting contact, the pressure-generating and intermediate contacts cooperating to establish a pressure-generating arc, the intermediate andinterrupting contacts cooperating to estab lish an interrupting are, an operating rod for ac- I tuating the pressure-generating contact, a piston chamber, a piston movable within the piston chamber'ancl having its two sides exposed to the arcing pressure, passage means communicating the piston chamber on the working side thereof only with the pressure-generating arc, means biasing. the operating rod in a direction to move liquid toward the pressure-generating are, means interconnecting the operating rod with the piston, a member of relatively enlarged cross-sectional area movable with the operating rod and a member of relatively srnall cross-sectional area movable thereby, the operating rod being movable through the piston chamber so that the enlarged member enters the piston'chamber as the smaller member leaves .the piston chamber so that a positive diminution of liquid takes place within the piston chamber, means venting the interrupting are, and second passage means interconnecting the pressure-generating arc with the interrupting arc.

4. A circuit interrupter including a pressuregeneratingcontact, an intermediate contact and an interrupting contact, the pressure-generating and intermediate contacts cooperating to establish .a pressure-generating arc, the intermediate and interrupting contacts cooperating to estab-.

lish an interrupting are, an operating rod for actuating the pressure-generating contact, a piston chamber, a piston movable within the piston chamber and having its two sides exposed to the arcing pressure, passage means communicating the piston chamber on the working side thereof only with the pressure-generating are, means biasing the operating rod in a direction to move liquid toward the pressure-generating are, means interconnecting the operating rod with the piston, a member of relatively enlarged cross-sectional area movable with the operating rod and a member of relatively small cross-sectional area movable thereby, the operating rod being movable through the piston chamber so that the enlarged member enters the piston chamber as the smaller member leaves the piston chamber so that a positive diminution of liquid takes place within the piston chamber, the interconnecting means between the operating rod and the piston utilizing a lost-motion connection, means venting the interrupting arc, and second passage means interconnecting the pressure-generating arc with the interrupting arc.

5. A circuit interrupter of the liquid-break type including an arc-extinguishing unit, contact means for establishing an are within the unit, an operating rod for actuating the contact means, a piston chamber, a piston movable within the piston chamber and having its two sides exposed to the arcing pressure, passage means communicating the piston chamber on the working side thereof with the established are, means biasing the operating rod in a direction to move liquid toward the established are, means interconnecting the operating rod with the piston, a member of relatively enlarged cross-sectional area movable with the operating rod and a member of relatively small cross-sectional area movable thereby, and the operating rod being movable through the piston chamber so that the enlarged member enters the piston chamber as the smaller member leaves the piston chamber so that a positive diminution of liquid takes place within the piston chamber.

ROBERT E. FRIEDRICH.

CARL G. LENTJES.

REFERENCES CITED lhe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,258,226 Skeats Oct. '1, 1941 2,271,989 Prince Feb. 3, 1942 2,422,569 Leeds June 1'7, 194'? 2,445,442 Leeds et al. July 20, 1948 2,462,724 Cumming Feb. 22, 1949 

